2000 crown vic random misfires, car stalls

[rey silvas]

Where to start.... okay I have a 2000 crown vic, police interceptor..... 1st.. car started idling rough had the codes read gave misfire on 4 . So we had the boots and spark plugs replaced. Car ran fine for like 3 days then engine light came on again.. running rough... code read misfire in 8 so had the coils on 4 and 8 replaced... ran fine for all of 2 wks. Again engine light came on... now showing a misfire on 7, but car runs fine..??. Anyways I noticed my battery gage was marking a really low charge... but as soon as I would get on higway it would jump back up to normal... it did this for a couple weeks, then I noticed the gage was marking really low car was losing power... mind you I have a new battery and alternator on car already. But still I had them tested;d both tested fine... Then car kept stalling at stop signs ans red lights awent ahead and exchanged alternator 4since its under waranty anyway. This helped the charge gage was reading normal.. but car still kept dying... so replaced fuel filter... didn't help replaced tps and mass air flow sensors too...but it still keeps dying on me. Now codes are coming up misfires on 4&8!!!! I don't understand and no one else sems to have any ideei,. Why does my car keep stalling and what wouldcause these random misfires especially when these coils have been replaced already??? Please help!

[DeltaP]

In your last sentence you used the term "Random misfire". If that is one of the codes I was getting I'd check for a vacuum leak. I'd also check all my engine and chassis grounds as well as battery cables for corrosion,swelling and high resistance. If some of this goes away I'd give it a full tune up including all plugs and coils. They are a problem w/them 4.6's.

[rey silvas]

It's not reading a random misfire I'm just meaning the misfire keeps jumping 1 day it'll be on 7 then the next on 8 then 4..... it keeps jumping....... it has new plugs and boots and coils.

[danielsatur]

Random misfires on random cylinders -

Air - bad air filter, bad or dirty MAF sensor, dirty throttle body, unmetered air leaks on air intake.

Fuel - bad fuel filter, fuel regulator, or fuel pump.

Ignition - bad or dirty crank, or cam sensors.
.

Exhaust - plugged catalytic converters.

Action -
1) Replace both air/fuel filters.
2) Clean MAF sensor with CRC MAF cleaner.
3) Check fuel pressure
4) Reset/clear codes
5) Again - Have both the alternator + battery load tested @ local auto parts store for free.
6) Also do a battery drain test done with engine off & key out
7) Have a back pressure test done cheap/free @ a local muffler shop.
8) Monitor

[rey silvas]

Thanks somebofbthis stuff has already been done numerous times. But I will definitely have the fuel pressure tested and go to muffler shop Monday. Thanks again and I'll let you know how it goes.

[danielsatur]

DIY smoke test to rule out any unmetered air leaks on air Intake system.

$150 Professional Test- www.youtube.com/watch?v=FfiQ7qWiG-M
$1.50 Shade Tree Test - www.youtube.com/watch?v=zMok2y05jNE , try using plastic wrap around the air filter to block all air incoming to the Intake, PCV hose to blow smoke, Black & mild cigar, and favorite beer for better results. Put your thumb over PCV tube in between puffs of smoke.

Lynyrd Skynyrd ''That smell'' www.youtube.com/watch?v=hQlCxE4z3u4

Focus on the EGR, PCV, and Air intake system for any smoke leaks, because of bad plastic, rubber, gaskets, and seals.